Do White Noise Machines Work?

When I gave up my home for a life on the road, that also meant giving up my beloved sleepy-time fan. Ever since the days of noisy dorm living, I've slept with a small fan whirring in the background. This not only blocked out background noise, but gave me a sense of consistency, a cue to my brain that it's time to sleep.

Now that I'm living on the road, my small carry-on bags don't have room for a fan, and I no matter how nice a place looks online, I never know what it will sound like until I arrive and try to catch a few z's. I downloaded a white noise app for my phone which simulates a fan's hum, but just isn't quite the same. It works just fine for the time being, but I wonder — do white noise machines work for you?